1. Field of the Invention
The present invention relates generally to a silver halide color photographic material and in particular it relates to a silver halide color photographic material providing a stabilized color image.
2. Description of the Prior Art
It is known that when a silver halide color photographic material is subjected to color development after imagewise exposure, the oxidized aromatic primary amino color developing agent reacts with a dye forming coupler in the color photographic material to form an indoaniline, indophenol, indamine, phenoxazine, azomethine, or similar dye, which results in the formation of a color image. In the known system a subtractive color process is usually used for color reproduction and yellow, magneta, and cyan color images are formed which are in complementary color relations to blue, green, and red colors, respectively. In general, an acylacetamido type coupler is used for forming a yellow dye image, a pyrazolone, cyanoacetyl, or indazolone type coupler is used for forming a magneta dye image, and a phenol or naphthol type coupler is used for forming a cyan dye image.
In such color photography, the dye forming couplers (hereinafter, designated simply "couplers") are incorporated in a color developer or in the light-sensitive photographic emulsion layers of a color photographic material to make it thus possible to cause a reaction in the photographic emulsion layers, during color development, of the couplers and the oxidation product of a color developing agent formed in the case of developing the latent images formed in the silver halide emulsion layers. In this case the couplers incorporated in the color developer are diffusible while the couplers incorporated in the photographic emulsion layers are non-diffusible.
Many phenolic or naphtholic couplers for forming cyan dye images in the above-described color photographic system are known but the cyan dye images formed by such phenolic or naphtholic couplers fade markedly when the photographs are stored for a long period of time. Color photographs are sometimes stored in such a state that they are always exposed to light (for instance, they are stored under the exposure of very intensive light or stored under a mild exposure condition as in the case of exhibitions of large-size color transparencies, color papers, color slides, etc.) or color photographs are sometimes stored in the dark for a long period of time with short light exposures (for instance, color positive cinefilms, color prints stored in albums, color slides stored in boxes, and color negative films stored in folders). The discoloration and fading of color images occurring under these latter storage conditions are caused by moisture or a small amount of chemical materials present in the surrounding atmosphere or further caused by heat and they are different from the light fading in the former case as the fading in the dark or the thermal fading. It is generally well known the occurrence of the fading in the dark or thermal fading of cyan dye images is quite severe as compared to those of yellow dye images and magneta dye images. The occurrence of this severe fading in the dark and thermal fading of the cyan dye images gives rise to obstacles in using color photographs as recording materials for semi-permanent storage. For instance, even if the extent of fading of the cyan dye images is low, the color balance of the color photograph is destroyed since the fastness of the cyan dye images differs from the fastness of the yellow dye images and the fastness of the magneta dye images and thus the level of fastness of the cyan dye images must be increased to at least the levels of the fastness of the other dye images.
Various attempts have hitherto been proposed for improving the fading in the dark and the thermal fading of cyan dye images. For instance, the fastness of the cyan dye images can be improved by processing the color photograph in a stabilization bath containing the hydantoin compound as described in U.S. Pat. No. 2,579,436; the carbohydrazide as described in U.S. Pat. No. 3,201,244; the tetramethylol ring alcohol as described in U.S. Pat. No. 2,983,607; the saccharide or the aminoacid derivative as described in U.S. Pat. Nos. 3,095,302 and 3,291,606; the cysteine as described in U.S. Pat. No. 3,201,243; the polymethylol compound as described in U.S. Pat. No. 3,473,929; the organic agent for preventing the occurrence of ferrotype fogging (e.g., mercaptans and the tautomers thereof, seleno alcohols, and heterocyclic ring compounds having an imino group) as described in Japanese Patent Publication No. 18257/1963; or the compounds as described in U.S. Pat. Nos. 3,676,136 and 3,666,468 and Japanese Patent Publication No. 47245/1972. However, these methods as shown above are still insufficient for improving the fastness of the cyan dye images and also in these methods the above-described compounds must be incorporated in the processing bath in an amount as large as about 0.5 to 20% by weight. This results in making the surfaces of color photographs thus processed sticky and gives rise to undesirable difficulties such as adhesion when they are pasted in an album.
Furthermore, an attempt has also been proposed, as described in Japanese Patent Publication No. 32728/1973, in which the compound as described in that Japanese Patent specification is incorporated in the photographic emulsion layer but the effect obtained by the method is also insufficient as is the situation with the above-described methods.
Also, since it is generally believed that the couplers remaining unreacted in the developed color photograph accelerate the fading of color images, removal of such remaining couplers has been proposed. For instance, a method in which the unreacted couplers are split into low molecular fragments during development processing and the fragments are removed by diffusion from the emulsion layers, as described in British Pat. Nos. 843,940 and 849,065, and a method in which a water-soluble coupler having a water-solubilizing group at the coupling position is incorporated in the photographic emulsion layer for protecting the dye formed by the color development from the influence of the coupler and further a dispersion of a hydrophobic solvent which does not have a solvent action for the coupler but has a strong solvent action to the dye formed from the coupler as described in U.S. Pat. No. 3,271,152, are known.
However, the former method involves complex production steps in that a processing bath for splitting the unreacted coupler into low molecular fragments is additionally required and the latter method is complex in that the water-soluble coupler and the hydrophobic solvent have to be dispersed separately in the emulsion layer. Thus, both methods are not practical methods.
Moreover, there is a method of improving the fastness of dye images by over-coating a transparent polymer film such as a polystyrene film and a polyethylene film on the surface of a color photograph after developing the material as described in U.S. Pat. No. 3,614,839 and British Pat. Nos. 1,167,519 and 1,151,771. However, the method not only requires the troublesome step of laminating the overcoat but also does not provide a sufficiently high effect of improving fading in the dark and thermal fading of the cyan dye images.